BACKGROUND:
The use of antimicrobial drugs in the treatment of gonorrhea began in 1930 with
the use of sulfonamides. Through the years, other drugs such as penicillin,
spectinomycin, tetracycline among others, came into use. Although highly efficient
at first, with the passing of time these drugs began to present untoward therapeutic
results, because of the appearance of cases with chromosomic and plasmidial
resistance. Because of this, in order to establish a program to combat and control
a determined bacterial morbidity, it was necessary to carry out a program of
epidemiologic surveillance evaluating the sensitivity behavior of the etiologic
agents against the various therapeutic agents. OBJECTIVES AND METHODS: The objective of this work was to evaluate the
susceptibility of strains of Neisseria gonorrhoeae to the five drugs which are
mostly used for the treatment of gonorrhea in Brazil (pencillin; cefoxitine;
tetracycline; thiamphenicol and spectinomycine), by Minimum Inhibitory Concentration.
RESULTS AND CONCLUSION: We concluded that drugs such as cefoxitine, thiamphenicol
and spectinomycine are still excellent drugs for the treatment of gonorrhea.
Although penicillin continues to be effective, its use requires greater care,
due to the emergence of resistant strains, and tetracycline must be absolutely
avoided for the treatment of gonorrhea.

Gonorrhea represents
one of humanity's oldest morbid states. Urethral secretions of venereal origin,
supposedly gonococcicides, were already described by the Chinese during the
empire of Huang Ti in 2637 BC. The utilization of antimicrobial agents in its
therapeutics began in the 1930s with sulfonamides.1 However, in spite
of being highly effective, resistance to these drugs grew quickly,2,3
since resistance mechanisms were favored by selective potency following the
heavy use of these drugs. With the emergence of penicillin, the therapeutics
of gonorrhea took new directions. Although in 1943 this drug proved effective,
already by the end of the decade of the 1950's several reports pointed to a
reduction in the sensitivity of gonococcus to penicillin.6-10 Starting
from the beginning of the 80's, reports relating to the resistance to spectinomycin11,12and
to cephalosporins13,14,15 also began to appear. From the above it
is clear that a good strategy to combat and control certain bacterial morbidity
should anticipate a program of epidemiologic vigilance, monitoring the sensitivity
reactions of the etiological agents, as well as other procedures. From the epidemiological
point of view it is known today that cultural issues in certain segments of
the population are of capital importance in the phenomenon of selective potency16,17,18
of the various etiological agents. Among these cultural aspects that stand out
are the indiscriminate use of antibiotics that, according to the World Health
Organization are linked to social pressures arising from the stigma that accompanies
sexually transmissible diseases.19 Self-medication, lay diagnosis,16,20,21
and attendance at drugstore counters, had occurred in 90% of the first consultations
for sexually transmissible diseases.20,22,23 Finally, further complicating
the cultural aspects in the continuation of the phenomenon of selective potency,
there exists with equal importance the inopportune action of doctors, fomenting
the excessive use of antimicrobial drugs, whether at private clinics, or under
official recommendations in health programs.19

Even before the
development of other phenotypic techniques, the behavior of sensitivity was,
among other parameters, used to characterize the strains of Neisseria gonorrhoeae,
his behavior was correlated to other serious diseases, as well as to the various
geographical areas.24 However, the emergence of new techniques facilitated
this work. At the present time the best tool for programs of epidemiologic surveillance,
playing the part of an epidemiological indicator of sensitivity behavior to
antimicrobial drugs, is the current and more precise methodology known as Minimum
Inhibitory Concentration (MIC).25 The purpose of this present work
is to evaluate the current sensitivity, through MIC to the five main drugs used
in the treatment of gonorrhea in Brazil (penicillin; cefoxitin; tetracycline;
thiamphenicol and spectinomycin).

MATERIAL AND
METHODS

This study was
accomplished using strains of Neisseria gonorrhoeae obtained from patients
presenting acute but not complex gonorrhea, of both sexes, being treated at
the Sexually Transmissible Diseases Service of the Dermatology Division of the
Hospital das Clínicas, Faculty of Medicine, University of São Paulo and Sexually
Transmissible Diseases Service of the Centro de Saúde Escola Geraldo de Paula
Souza, Faculty of Public Health, University of São Paulo.

In the period from
July 1998 to February of 2000, 65 strains of Neisseria gonorrhoeae were
isolated.

The strains were
isolated in modified Thayer-Martin medium 26 and later identified by direct
bacterioscopy with Gram coloration, by reaction of the enzyme cytochrome-oxidase
and by reaction of acidification of sugars.27-31 The strains were
also submitted to chromogenic cephalosporin test for isolation of the betalactamase
enzyme.32-36

In the studied
population 15 strains were isolated of Neisseria gonorrhoeae producing
penicillins (NGPP).

All strains were
submitted to the susceptibility test using MIC technique with dilution in Agar.37-40
In the sensitivity test, the five drugs that are the most used in the treatment
of gonorrhea were utilized: penicillin, cefoxitin, tetracycline, thiamphenicol
and spectinomycin. The drugs tested were prepared according to appropriate techniques41,42
and in such a way as to obtain the following final concentrations:

The inoculations
were prepared starting with a subculture of each Neisseria gonorrhoeae,
with a variation of from 18 to 24 hours of growth in medium under appropriate
conditions.26,31,43 The MIC was read from the lowest concentration
required for total inhibition of bacterial growth. Interpretation of the results,
summarized in table 1, was
made according to norms of the National Committee for Clinical Laboratory Standards
- NCCLS.38

RESULTS

The results of
the sensitivity of the 50 strains of Neisseria gonorrhoeae not producing
penicillinase are presented in table
2, and, likewise, the results of the 15 strains of NGPPs, in table
3. The comparative result is expressed in table
4, and the distribution among the 65 strains, according to the tested drugs,
in table 5.

DISCUSSION

In relation to
cefoxitin, the strains not producing penicillinase presented their MIC more
frequently in 0.125mg/ml, while NGPPs demonstrated a greater tolerance to this
drug, presenting a 0.5mg/ml MIC more frequently, followed by 2mg/ml. Table
5 shows homogeneity in the behavior of sensitivity of the NGPP strains,
which present a smaller variation than those not producing penicillinase, however
with higher levels of tolerance to cefoxitin than those not producing penicillinase.
The phenomenon observed was the deviation in the mean and median values. Among
the strains not producing penicillinase the mean was 0.515mg/ml, and median
0.125mg/ml, passing the NGPPs to present a mean of 1.084mg/ml and median 0.5mg/ml.
The same occurs with MIC50, that passes from 0.0919mg/ml among those
not producing penicillinase to 0.5833mg/ml among NGPPs. And MIC90
repeats the phenomenon, passing from 0.9545mg/ml to 1.7mg/ml among those not
producing penicillinase and NGPPs, respectively. As can be seen, the process
of toleration among the strains of Neisseria gonorrhoeae is disturbing.

In relation to
tetracycline, as was observed in this work, there was a variation between the
strains not producing penicillinase that was not found among the NGPPs. In spite
of the fact that of the values of MIC90 for the two similar populations,
the mean (0.985mg/ml) distribution frequency (0.5mg/ml) and MIC50(0.4583mg/ml)
observed among those not producing penicillinase, compared with the statistics
relative to NGPPs, were practically double.

As for the sensitivity
behavior to thiamphenicol, the two populations studied (producers and non producers
of penicillinase) presented a homogeneous variation. The mean (1.625mg/ml) and
median, with bimodal values (0.5 and 1mg/ml), observed in the strains not producing
penicillinase, represent values of 2.384mg/ml and 4mg/ml, respectively, among
the NGPP strains. The values of MIC50 for thiamphenicol are a repetition
of this behavior, 0.7333mg/ml among those not producing penicillinase and 1.7mg/ml
among NGPPs; however, in relation to MIC90 for thiamphenicol, the
observed alterations are negligible.

In relation to
spectinomycin, the variation observed between the NGPP strains was greater than
that observed among the strains not producing penicillinase. Although the average
and MIC90had increased, MIC50 was less among the NGPPs.
Although reports exist of chromosomal resistance to spectinomycin among the
strains of Neisseria gonorrhoeae, occurrence of this phenomenon was not
observed in the present work.

Finally, in relation
to penicillin, for the NGPP strains all the values were above the sensitivity
limits.

The detection of
strains other than NGPPs that were presented with MIC and that fell in the intermediate
classification of sensitivity between cefoxitin and thiamphenicol, and of NGPP
strains with intermediate MIC of sensitivity between thiamphenicol and spectinomycin,
is a warning signal. It reinforces the need for the use of more rigorous criteria
in the prescription of these drugs that, in spite of still being highly effective
in the treatment of gonorrhea, already present indications in the laboratory
that suggest they may also be heading toward a loss of effectiveness in the
treatment of the disease, with the possibility of allowing the emergence of
chromosomal or even plasmidial resistance to these drugs.

CONCLUSION

In conclusion,
drugs such as cefoxitin, thiamphenicol and spectinomycin as yet continue to
constitute excellent drugs for the treatment of gonorrhea. Penicillin, although
still effective, requires greater care in its use due to the appearance of resistant
strains. In relation to tetracycline, its use in the treatment of gonorrhea
in Brazil at this time presents risks and its prescription clearly should be
contraindicated.

In view of the
results obtained, it can be concluded that most of the tested drugs present
satisfactory results in the treatment of gonorrhea.

Received in November,
29th of 2001
Approved by the Consultive Council and accepted for publication in July, 31st
of 2002

*
Work conducted at the Service of Sexually Transmitted Diseases of the Dermatology
Division, "Hospital das Clínicas da Faculdade de Medicina da Universidade
de São Paulo" and at the Service of Sexually Transmitted Diseases, "Centro
de Saúde Escola Geraldo de Paula Souza da Faculdade de Saúde Pública
da Universidade de São Paulo".